/**
 * @file
 * Sockets BSD-Like API module
 *
 */

/*
 * Copyright (c) 2001-2004 Swedish Institute of Computer Science.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without modification,
 * are permitted provided that the following conditions are met:
 *
 * 1. Redistributions of source code must retain the above copyright notice,
 *    this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright notice,
 *    this list of conditions and the following disclaimer in the documentation
 *    and/or other materials provided with the distribution.
 * 3. The name of the author may not be used to endorse or promote products
 *    derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT
 * SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
 * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
 * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
 * OF SUCH DAMAGE.
 *
 * This file is part of the lwIP TCP/IP stack.
 *
 * Author: Adam Dunkels <adam@sics.se>
 *
 * Improved by Marc Boucher <marc@mbsi.ca> and David Haas <dhaas@alum.rpi.edu>
 *
 */

#include "lwip/opt.h"

#if LWIP_SOCKET /* don't build if not configured for use in lwipopts.h */

#include "lwip/sockets.h"
#include "lwip/api.h"
#include "lwip/sys.h"
#include "lwip/igmp.h"
#include "lwip/inet.h"
#include "lwip/tcp.h"
#include "lwip/raw.h"
#include "lwip/udp.h"
#include "lwip/tcpip.h"
#include "lwip/pbuf.h"
#if LWIP_CHECKSUM_ON_COPY
#include "lwip/inet_chksum.h"
#endif

#include <string.h>

#define NUM_SOCKETS MEMP_NUM_NETCONN

/** Contains all internal pointers and states used for a socket */
struct lwip_sock
{
    /** sockets currently are built on netconns, each socket has one netconn */
    struct netconn *conn;
    /** data that was left from the previous read */
    void *lastdata;
    /** offset in the data that was left from the previous read */
    u16_t lastoffset;
    /** number of times data was received, set by event_callback(),
        tested by the receive and select functions */
    s16_t rcvevent;
    /** number of times data was ACKed (free send buffer), set by event_callback(),
        tested by select */
    u16_t sendevent;
    /** error happened for this socket, set by event_callback(), tested by select */
    u16_t errevent;
    /** last error that occurred on this socket */
    int err;
    /** counter of how many threads are waiting for this socket using select */
    int select_waiting;
};

/** Description for a task waiting in select */
struct lwip_select_cb
{
    /** Pointer to the next waiting task */
    struct lwip_select_cb *next;
    /** Pointer to the previous waiting task */
    struct lwip_select_cb *prev;
    /** readset passed to select */
    fd_set *readset;
    /** writeset passed to select */
    fd_set *writeset;
    /** unimplemented: exceptset passed to select */
    fd_set *exceptset;
    /** don't signal the same semaphore twice: set to 1 when signalled */
    int sem_signalled;
    /** semaphore to wake up a task waiting for select */
    sys_sem_t sem;
};

/** This struct is used to pass data to the set/getsockopt_internal
 * functions running in tcpip_thread context (only a void* is allowed) */
struct lwip_setgetsockopt_data
{
    /** socket struct for which to change options */
    struct lwip_sock *sock;
#ifdef LWIP_DEBUG
    /** socket index for which to change options */
    int s;
#endif /* LWIP_DEBUG */
    /** level of the option to process */
    int level;
    /** name of the option to process */
    int optname;
    /** set: value to set the option to
      * get: value of the option is stored here */
    void *optval;
    /** size of *optval */
    socklen_t *optlen;
    /** if an error occures, it is temporarily stored here */
    err_t err;
};

/** The global array of available sockets */
static struct lwip_sock sockets[NUM_SOCKETS];
/** The global list of tasks waiting for select */
static struct lwip_select_cb *select_cb_list;
/** This counter is increased from lwip_select when the list is chagned
    and checked in event_callback to see if it has changed. */
static volatile int select_cb_ctr;

/** Table to quickly map an lwIP error (err_t) to a socket error
  * by using -err as an index */
static const int err_to_errno_table[] =
{
    0,             /* ERR_OK          0      No error, everything OK. */
    ENOMEM,        /* ERR_MEM        -1      Out of memory error.     */
    ENOBUFS,       /* ERR_BUF        -2      Buffer error.            */
    EWOULDBLOCK,   /* ERR_TIMEOUT    -3      Timeout                  */
    EHOSTUNREACH,  /* ERR_RTE        -4      Routing problem.         */
    EINPROGRESS,   /* ERR_INPROGRESS -5      Operation in progress    */
    EINVAL,        /* ERR_VAL        -6      Illegal value.           */
    EWOULDBLOCK,   /* ERR_WOULDBLOCK -7      Operation would block.   */
    EADDRINUSE,    /* ERR_USE        -8      Address in use.          */
    EALREADY,      /* ERR_ISCONN     -9      Already connected.       */
    ECONNABORTED,  /* ERR_ABRT       -10     Connection aborted.      */
    ECONNRESET,    /* ERR_RST        -11     Connection reset.        */
    ENOTCONN,      /* ERR_CLSD       -12     Connection closed.       */
    ENOTCONN,      /* ERR_CONN       -13     Not connected.           */
    EIO,           /* ERR_ARG        -14     Illegal argument.        */
    -1,            /* ERR_IF         -15     Low-level netif error    */
};

#define ERR_TO_ERRNO_TABLE_SIZE \
  (sizeof(err_to_errno_table)/sizeof(err_to_errno_table[0]))

#define err_to_errno(err) \
  ((unsigned)(-(err)) < ERR_TO_ERRNO_TABLE_SIZE ? \
    err_to_errno_table[-(err)] : EIO)

#ifdef ERRNO
#ifndef set_errno
#define set_errno(err) errno = (err)
#endif
#else /* ERRNO */
#define set_errno(err)
#endif /* ERRNO */

#define sock_set_errno(sk, e) do { \
  sk->err = (e); \
  set_errno(sk->err); \
} while (0)

/* Forward delcaration of some functions */
static void event_callback(struct netconn *conn, enum netconn_evt evt, u16_t len);
static void lwip_getsockopt_internal(void *arg);
static void lwip_setsockopt_internal(void *arg);

/**
 * Initialize this module. This function has to be called before any other
 * functions in this module!
 */
void
lwip_socket_init(void)
{
}

/**
 * Map a externally used socket index to the internal socket representation.
 *
 * @param s externally used socket index
 * @return struct lwip_sock for the socket or NULL if not found
 */
static struct lwip_sock *
get_socket(int s)
{
    struct lwip_sock *sock;

    if ((s < 0) || (s >= NUM_SOCKETS))
    {
        LWIP_DEBUGF(SOCKETS_DEBUG, ("get_socket(%d): invalid\n", s));
        set_errno(EBADF);
        return NULL;
    }

    sock = &sockets[s];

    if (!sock->conn)
    {
        LWIP_DEBUGF(SOCKETS_DEBUG, ("get_socket(%d): not active\n", s));
        set_errno(EBADF);
        return NULL;
    }

    return sock;
}

/**
 * Same as get_socket but doesn't set errno
 *
 * @param s externally used socket index
 * @return struct lwip_sock for the socket or NULL if not found
 */
static struct lwip_sock *
tryget_socket(int s)
{
    if ((s < 0) || (s >= NUM_SOCKETS))
    {
        return NULL;
    }
    if (!sockets[s].conn)
    {
        return NULL;
    }
    return &sockets[s];
}

/**
 * Allocate a new socket for a given netconn.
 *
 * @param newconn the netconn for which to allocate a socket
 * @param accepted 1 if socket has been created by accept(),
 *                 0 if socket has been created by socket()
 * @return the index of the new socket; -1 on error
 */
static int
alloc_socket(struct netconn *newconn, int accepted)
{
    int i;
    SYS_ARCH_DECL_PROTECT(lev);

    /* allocate a new socket identifier */
    for (i = 0; i < NUM_SOCKETS; ++i)
    {
        /* Protect socket array */
        SYS_ARCH_PROTECT(lev);
        if (!sockets[i].conn)
        {
            sockets[i].conn       = newconn;
            /* The socket is not yet known to anyone, so no need to protect
               after having marked it as used. */
            SYS_ARCH_UNPROTECT(lev);
            sockets[i].lastdata   = NULL;
            sockets[i].lastoffset = 0;
            sockets[i].rcvevent   = 0;
            /* TCP sendbuf is empty, but the socket is not yet writable until connected
             * (unless it has been created by accept()). */
            sockets[i].sendevent  = (newconn->type == NETCONN_TCP ? (accepted != 0) : 1);
            sockets[i].errevent   = 0;
            sockets[i].err        = 0;
            sockets[i].select_waiting = 0;
            return i;
        }
        SYS_ARCH_UNPROTECT(lev);
    }
    return -1;
}

/** Free a socket. The socket's netconn must have been
 * delete before!
 *
 * @param sock the socket to free
 * @param is_tcp != 0 for TCP sockets, used to free lastdata
 */
static void
free_socket(struct lwip_sock *sock, int is_tcp)
{
    void *lastdata;
    SYS_ARCH_DECL_PROTECT(lev);

    lastdata         = sock->lastdata;
    sock->lastdata   = NULL;
    sock->lastoffset = 0;
    sock->err        = 0;

    /* Protect socket array */
    SYS_ARCH_PROTECT(lev);
    sock->conn       = NULL;
    SYS_ARCH_UNPROTECT(lev);
    /* don't use 'sock' after this line, as another task might have allocated it */

    if (lastdata != NULL)
    {
        if (is_tcp)
        {
            pbuf_free((struct pbuf *)lastdata);
        }
        else
        {
            netbuf_delete((struct netbuf *)lastdata);
        }
    }
}

/* Below this, the well-known socket functions are implemented.
 * Use google.com or opengroup.org to get a good description :-)
 *
 * Exceptions are documented!
 */

int
lwip_accept(int s, struct sockaddr *addr, socklen_t *addrlen)
{
    struct lwip_sock *sock, *nsock;
    struct netconn *newconn;
    ip_addr_t naddr;
    u16_t port;
    int newsock;
    struct sockaddr_in sin;
    err_t err;
    SYS_ARCH_DECL_PROTECT(lev);

    LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_accept(%d)...\n", s));
    sock = get_socket(s);
    if (!sock)
    {
        return -1;
    }

    if (netconn_is_nonblocking(sock->conn) && (sock->rcvevent <= 0))
    {
        LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_accept(%d): returning EWOULDBLOCK\n", s));
        sock_set_errno(sock, EWOULDBLOCK);
        return -1;
    }

    /* wait for a new connection */
    err = netconn_accept(sock->conn, &newconn);
    if (err != ERR_OK)
    {
        LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_accept(%d): netconn_acept failed, err=%d\n", s, err));
        if (netconn_type(sock->conn) != NETCONN_TCP)
        {
            sock_set_errno(sock, EOPNOTSUPP);
            return EOPNOTSUPP;
        }
        sock_set_errno(sock, err_to_errno(err));
        return -1;
    }
    LWIP_ASSERT("newconn != NULL", newconn != NULL);
    /* Prevent automatic window updates, we do this on our own! */
    netconn_set_noautorecved(newconn, 1);

    /* get the IP address and port of the remote host */
    err = netconn_peer(newconn, &naddr, &port);
    if (err != ERR_OK)
    {
        LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_accept(%d): netconn_peer failed, err=%d\n", s, err));
        netconn_delete(newconn);
        sock_set_errno(sock, err_to_errno(err));
        return -1;
    }

    /* Note that POSIX only requires us to check addr is non-NULL. addrlen must
     * not be NULL if addr is valid.
     */
    if (NULL != addr)
    {
        LWIP_ASSERT("addr valid but addrlen NULL", addrlen != NULL);
        memset(&sin, 0, sizeof(sin));
        sin.sin_len = sizeof(sin);
        sin.sin_family = AF_INET;
        sin.sin_port = htons(port);
        inet_addr_from_ipaddr(&sin.sin_addr, &naddr);

        if (*addrlen > sizeof(sin))
            *addrlen = sizeof(sin);

        MEMCPY(addr, &sin, *addrlen);
    }

    newsock = alloc_socket(newconn, 1);
    if (newsock == -1)
    {
        netconn_delete(newconn);
        sock_set_errno(sock, ENFILE);
        return -1;
    }
    LWIP_ASSERT("invalid socket index", (newsock >= 0) && (newsock < NUM_SOCKETS));
    LWIP_ASSERT("newconn->callback == event_callback", newconn->callback == event_callback);
    nsock = &sockets[newsock];

    /* See event_callback: If data comes in right away after an accept, even
     * though the server task might not have created a new socket yet.
     * In that case, newconn->socket is counted down (newconn->socket--),
     * so nsock->rcvevent is >= 1 here!
     */
    SYS_ARCH_PROTECT(lev);
    nsock->rcvevent += (s16_t)(-1 - newconn->socket);
    newconn->socket = newsock;
    SYS_ARCH_UNPROTECT(lev);

    LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_accept(%d) returning new sock=%d addr=", s, newsock));
    ip_addr_debug_print(SOCKETS_DEBUG, &naddr);
    LWIP_DEBUGF(SOCKETS_DEBUG, (" port=%"U16_F"\n", port));

    sock_set_errno(sock, 0);
    return newsock;
}

int
lwip_bind(int s, const struct sockaddr *name, socklen_t namelen)
{
    struct lwip_sock *sock;
    ip_addr_t local_addr;
    u16_t local_port;
    err_t err;
    const struct sockaddr_in *name_in;

    sock = get_socket(s);
    if (!sock)
    {
        return -1;
    }

    /* check size, familiy and alignment of 'name' */
    LWIP_ERROR("lwip_bind: invalid address", ((namelen == sizeof(struct sockaddr_in)) &&
               ((name->sa_family) == AF_INET) && ((((mem_ptr_t)name) % 4) == 0)),
               sock_set_errno(sock, err_to_errno(ERR_ARG)); return -1;);
    name_in = (const struct sockaddr_in *)(void *)name;

    inet_addr_to_ipaddr(&local_addr, &name_in->sin_addr);
    local_port = name_in->sin_port;

    LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_bind(%d, addr=", s));
    ip_addr_debug_print(SOCKETS_DEBUG, &local_addr);
    LWIP_DEBUGF(SOCKETS_DEBUG, (" port=%"U16_F")\n", ntohs(local_port)));

    err = netconn_bind(sock->conn, &local_addr, ntohs(local_port));

    if (err != ERR_OK)
    {
        LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_bind(%d) failed, err=%d\n", s, err));
        sock_set_errno(sock, err_to_errno(err));
        return -1;
    }

    LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_bind(%d) succeeded\n", s));
    sock_set_errno(sock, 0);
    return 0;
}

int
lwip_close(int s)
{
    struct lwip_sock *sock;
    int is_tcp = 0;

    LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_close(%d)\n", s));

    sock = get_socket(s);
    if (!sock)
    {
        return -1;
    }

    if(sock->conn != NULL)
    {
        is_tcp = netconn_type(sock->conn) == NETCONN_TCP;
    }
    else
    {
        LWIP_ASSERT("sock->lastdata == NULL", sock->lastdata == NULL);
    }

    netconn_delete(sock->conn);

    free_socket(sock, is_tcp);
    set_errno(0);
    return 0;
}

int
lwip_connect(int s, const struct sockaddr *name, socklen_t namelen)
{
    struct lwip_sock *sock;
    err_t err;
    const struct sockaddr_in *name_in;

    sock = get_socket(s);
    if (!sock)
    {
        return -1;
    }

    /* check size, familiy and alignment of 'name' */
    LWIP_ERROR("lwip_connect: invalid address", ((namelen == sizeof(struct sockaddr_in)) &&
               ((name->sa_family) == AF_INET) && ((((mem_ptr_t)name) % 4) == 0)),
               sock_set_errno(sock, err_to_errno(ERR_ARG)); return -1;);
    name_in = (const struct sockaddr_in *)(void *)name;

    if (name_in->sin_family == AF_UNSPEC)
    {
        LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_connect(%d, AF_UNSPEC)\n", s));
        err = netconn_disconnect(sock->conn);
    }
    else
    {
        ip_addr_t remote_addr;
        u16_t remote_port;

        inet_addr_to_ipaddr(&remote_addr, &name_in->sin_addr);
        remote_port = name_in->sin_port;

        LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_connect(%d, addr=", s));
        ip_addr_debug_print(SOCKETS_DEBUG, &remote_addr);
        LWIP_DEBUGF(SOCKETS_DEBUG, (" port=%"U16_F")\n", ntohs(remote_port)));

        err = netconn_connect(sock->conn, &remote_addr, ntohs(remote_port));
    }

    if (err != ERR_OK)
    {
        LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_connect(%d) failed, err=%d\n", s, err));
        sock_set_errno(sock, err_to_errno(err));
        return -1;
    }

    LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_connect(%d) succeeded\n", s));
    sock_set_errno(sock, 0);
    return 0;
}

/**
 * Set a socket into listen mode.
 * The socket may not have been used for another connection previously.
 *
 * @param s the socket to set to listening mode
 * @param backlog (ATTENTION: needs TCP_LISTEN_BACKLOG=1)
 * @return 0 on success, non-zero on failure
 */
int
lwip_listen(int s, int backlog)
{
    struct lwip_sock *sock;
    err_t err;

    LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_listen(%d, backlog=%d)\n", s, backlog));

    sock = get_socket(s);
    if (!sock)
    {
        return -1;
    }

    /* limit the "backlog" parameter to fit in an u8_t */
    backlog = LWIP_MIN(LWIP_MAX(backlog, 0), 0xff);

    err = netconn_listen_with_backlog(sock->conn, (u8_t)backlog);

    if (err != ERR_OK)
    {
        LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_listen(%d) failed, err=%d\n", s, err));
        if (netconn_type(sock->conn) != NETCONN_TCP)
        {
            sock_set_errno(sock, EOPNOTSUPP);
            return EOPNOTSUPP;
        }
        sock_set_errno(sock, err_to_errno(err));
        return -1;
    }

    sock_set_errno(sock, 0);
    return 0;
}

int
lwip_recvfrom(int s, void *mem, size_t len, int flags,
              struct sockaddr *from, socklen_t *fromlen)
{
    struct lwip_sock *sock;
    void             *buf = NULL;
    struct pbuf      *p;
    u16_t            buflen, copylen;
    int              off = 0;
    ip_addr_t        *addr;
    u16_t            port;
    u8_t             done = 0;
    err_t            err;

    LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_recvfrom(%d, %p, %"SZT_F", 0x%x, ..)\n", s, mem, len, flags));
    sock = get_socket(s);
    if (!sock)
    {
        return -1;
    }

    do
    {
        LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_recvfrom: top while sock->lastdata=%p\n", sock->lastdata));
        /* Check if there is data left from the last recv operation. */
        if (sock->lastdata)
        {
            buf = sock->lastdata;
        }
        else
        {
            /* If this is non-blocking call, then check first */
            if (((flags & MSG_DONTWAIT) || netconn_is_nonblocking(sock->conn)) &&
                    (sock->rcvevent <= 0))
            {
                if (off > 0)
                {
                    /* update receive window */
                    netconn_recved(sock->conn, (u32_t)off);
                    /* already received data, return that */
                    sock_set_errno(sock, 0);
                    return off;
                }
                LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_recvfrom(%d): returning EWOULDBLOCK\n", s));
                sock_set_errno(sock, EWOULDBLOCK);
                return -1;
            }

            /* No data was left from the previous operation, so we try to get
               some from the network. */
            if (netconn_type(sock->conn) == NETCONN_TCP)
            {
                err = netconn_recv_tcp_pbuf(sock->conn, (struct pbuf **)&buf);
            }
            else
            {
                err = netconn_recv(sock->conn, (struct netbuf **)&buf);
            }
            LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_recvfrom: netconn_recv err=%d, netbuf=%p\n",
                                        err, buf));

            if (err != ERR_OK)
            {
                if (off > 0)
                {
                    /* update receive window */
                    netconn_recved(sock->conn, (u32_t)off);
                    /* already received data, return that */
                    sock_set_errno(sock, 0);
                    return off;
                }
                /* We should really do some error checking here. */
                LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_recvfrom(%d): buf == NULL, error is \"%s\"!\n",
                                            s, lwip_strerr(err)));
                sock_set_errno(sock, err_to_errno(err));
                if (err == ERR_CLSD)
                {
                    return 0;
                }
                else
                {
                    return -1;
                }
            }
            LWIP_ASSERT("buf != NULL", buf != NULL);
            sock->lastdata = buf;
        }

        if (netconn_type(sock->conn) == NETCONN_TCP)
        {
            p = (struct pbuf *)buf;
        }
        else
        {
            p = ((struct netbuf *)buf)->p;
        }
        buflen = p->tot_len;
        LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_recvfrom: buflen=%"U16_F" len=%"SZT_F" off=%d sock->lastoffset=%"U16_F"\n",
                                    buflen, len, off, sock->lastoffset));

        buflen -= sock->lastoffset;

        if (len > buflen)
        {
            copylen = buflen;
        }
        else
        {
            copylen = (u16_t)len;
        }

        /* copy the contents of the received buffer into
        the supplied memory pointer mem */
        pbuf_copy_partial(p, (u8_t *)mem + off, copylen, sock->lastoffset);

        off += copylen;

        if (netconn_type(sock->conn) == NETCONN_TCP)
        {
            LWIP_ASSERT("invalid copylen, len would underflow", len >= copylen);
            len -= copylen;
            if ( (len <= 0) ||
                    (p->flags & PBUF_FLAG_PUSH) ||
                    (sock->rcvevent <= 0) ||
                    ((flags & MSG_PEEK) != 0))
            {
                done = 1;
            }
        }
        else
        {
            done = 1;
        }

        /* Check to see from where the data was.*/
        if (done)
        {
            ip_addr_t fromaddr;
            if (from && fromlen)
            {
                struct sockaddr_in sin;

                if (netconn_type(sock->conn) == NETCONN_TCP)
                {
                    addr = &fromaddr;
                    netconn_getaddr(sock->conn, addr, &port, 0);
                }
                else
                {
                    addr = netbuf_fromaddr((struct netbuf *)buf);
                    port = netbuf_fromport((struct netbuf *)buf);
                }

                memset(&sin, 0, sizeof(sin));
                sin.sin_len = sizeof(sin);
                sin.sin_family = AF_INET;
                sin.sin_port = htons(port);
                inet_addr_from_ipaddr(&sin.sin_addr, addr);

                if (*fromlen > sizeof(sin))
                {
                    *fromlen = sizeof(sin);
                }

                MEMCPY(from, &sin, *fromlen);

                LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_recvfrom(%d): addr=", s));
                ip_addr_debug_print(SOCKETS_DEBUG, addr);
                LWIP_DEBUGF(SOCKETS_DEBUG, (" port=%"U16_F" len=%d\n", port, off));
            }
            else
            {
#if SOCKETS_DEBUG
                if (netconn_type(sock->conn) == NETCONN_TCP)
                {
                    addr = &fromaddr;
                    netconn_getaddr(sock->conn, addr, &port, 0);
                }
                else
                {
                    addr = netbuf_fromaddr((struct netbuf *)buf);
                    port = netbuf_fromport((struct netbuf *)buf);
                }

                LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_recvfrom(%d): addr=", s));
                ip_addr_debug_print(SOCKETS_DEBUG, addr);
                LWIP_DEBUGF(SOCKETS_DEBUG, (" port=%"U16_F" len=%d\n", port, off));
#endif /*  SOCKETS_DEBUG */
            }
        }

        /* If we don't peek the incoming message... */
        if ((flags & MSG_PEEK) == 0)
        {
            /* If this is a TCP socket, check if there is data left in the
               buffer. If so, it should be saved in the sock structure for next
               time around. */
            if ((netconn_type(sock->conn) == NETCONN_TCP) && (buflen - copylen > 0))
            {
                sock->lastdata = buf;
                sock->lastoffset += copylen;
                LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_recvfrom: lastdata now netbuf=%p\n", buf));
            }
            else
            {
                sock->lastdata = NULL;
                sock->lastoffset = 0;
                LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_recvfrom: deleting netbuf=%p\n", buf));
                if (netconn_type(sock->conn) == NETCONN_TCP)
                {
                    pbuf_free((struct pbuf *)buf);
                }
                else
                {
                    netbuf_delete((struct netbuf *)buf);
                }
            }
        }
    }
    while (!done);

    if (off > 0)
    {
        /* update receive window */
        netconn_recved(sock->conn, (u32_t)off);
    }
    sock_set_errno(sock, 0);
    return off;
}

int
lwip_read(int s, void *mem, size_t len)
{
    return lwip_recvfrom(s, mem, len, 0, NULL, NULL);
}

int
lwip_recv(int s, void *mem, size_t len, int flags)
{
    return lwip_recvfrom(s, mem, len, flags, NULL, NULL);
}

int
lwip_send(int s, const void *data, size_t size, int flags)
{
    struct lwip_sock *sock;
    err_t err;
    u8_t write_flags;
    size_t written;

    LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_send(%d, data=%p, size=%"SZT_F", flags=0x%x)\n",
                                s, data, size, flags));

    sock = get_socket(s);
    if (!sock)
    {
        return -1;
    }

    if (sock->conn->type != NETCONN_TCP)
    {
#if (LWIP_UDP || LWIP_RAW)
        return lwip_sendto(s, data, size, flags, NULL, 0);
#else /* (LWIP_UDP || LWIP_RAW) */
        sock_set_errno(sock, err_to_errno(ERR_ARG));
        return -1;
#endif /* (LWIP_UDP || LWIP_RAW) */
    }

    write_flags = NETCONN_COPY |
                  ((flags & MSG_MORE)     ? NETCONN_MORE      : 0) |
                  ((flags & MSG_DONTWAIT) ? NETCONN_DONTBLOCK : 0);
    written = 0;
    err = netconn_write_partly(sock->conn, data, size, write_flags, &written);

    LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_send(%d) err=%d written=%"SZT_F"\n", s, err, written));
    sock_set_errno(sock, err_to_errno(err));
    return (err == ERR_OK ? (int)written : -1);
}

int
lwip_sendto(int s, const void *data, size_t size, int flags,
            const struct sockaddr *to, socklen_t tolen)
{
    struct lwip_sock *sock;
    err_t err;
    u16_t short_size;
    const struct sockaddr_in *to_in;
    u16_t remote_port;
#if !LWIP_TCPIP_CORE_LOCKING
    struct netbuf buf;
#endif

    sock = get_socket(s);
    if (!sock)
    {
        return -1;
    }

    if (sock->conn->type == NETCONN_TCP)
    {
#if LWIP_TCP
        return lwip_send(s, data, size, flags);
#else /* LWIP_TCP */
        LWIP_UNUSED_ARG(flags);
        sock_set_errno(sock, err_to_errno(ERR_ARG));
        return -1;
#endif /* LWIP_TCP */
    }

    /* @todo: split into multiple sendto's? */
    LWIP_ASSERT("lwip_sendto: size must fit in u16_t", size <= 0xffff);
    short_size = (u16_t)size;
    LWIP_ERROR("lwip_sendto: invalid address", (((to == NULL) && (tolen == 0)) ||
               ((tolen == sizeof(struct sockaddr_in)) &&
                ((to->sa_family) == AF_INET) && ((((mem_ptr_t)to) % 4) == 0))),
               sock_set_errno(sock, err_to_errno(ERR_ARG)); return -1;);
    to_in = (const struct sockaddr_in *)(void *)to;

#if LWIP_TCPIP_CORE_LOCKING
    /* Should only be consider like a sample or a simple way to experiment this option (no check of "to" field...) */
    {
        struct pbuf *p;
        ip_addr_t *remote_addr;

#if LWIP_NETIF_TX_SINGLE_PBUF
        p = pbuf_alloc(PBUF_TRANSPORT, short_size, PBUF_RAM);
        if (p != NULL)
        {
#if LWIP_CHECKSUM_ON_COPY
            u16_t chksum = 0;
            if (sock->conn->type != NETCONN_RAW)
            {
                chksum = LWIP_CHKSUM_COPY(p->payload, data, short_size);
            }
            else
#endif /* LWIP_CHECKSUM_ON_COPY */
                MEMCPY(p->payload, data, size);
#else /* LWIP_NETIF_TX_SINGLE_PBUF */
        p = pbuf_alloc(PBUF_TRANSPORT, short_size, PBUF_REF);
        if (p != NULL)
        {
            p->payload = (void *)data;
#endif /* LWIP_NETIF_TX_SINGLE_PBUF */

            if (to_in != NULL)
            {
                inet_addr_to_ipaddr_p(remote_addr, &to_in->sin_addr);
                remote_port = ntohs(to_in->sin_port);
            }
            else
            {
                remote_addr = &sock->conn->pcb.ip->remote_ip;
#if LWIP_UDP
                if (NETCONNTYPE_GROUP(sock->conn->type) == NETCONN_UDP)
                {
                    remote_port = sock->conn->pcb.udp->remote_port;
                }
                else
#endif /* LWIP_UDP */
                {
                    remote_port = 0;
                }
            }

            LOCK_TCPIP_CORE();
            if (netconn_type(sock->conn) == NETCONN_RAW)
            {
#if LWIP_RAW
                err = sock->conn->last_err = raw_sendto(sock->conn->pcb.raw, p, remote_addr);
#else /* LWIP_RAW */
                err = ERR_ARG;
#endif /* LWIP_RAW */
            }
#if LWIP_UDP && LWIP_RAW
            else
#endif /* LWIP_UDP && LWIP_RAW */
            {
#if LWIP_UDP
#if LWIP_CHECKSUM_ON_COPY && LWIP_NETIF_TX_SINGLE_PBUF
                err = sock->conn->last_err = udp_sendto_chksum(sock->conn->pcb.udp, p,
                                             remote_addr, remote_port, 1, chksum);
#else /* LWIP_CHECKSUM_ON_COPY && LWIP_NETIF_TX_SINGLE_PBUF */
                err = sock->conn->last_err = udp_sendto(sock->conn->pcb.udp, p,
                                                        remote_addr, remote_port);
#endif /* LWIP_CHECKSUM_ON_COPY && LWIP_NETIF_TX_SINGLE_PBUF */
#else /* LWIP_UDP */
                err = ERR_ARG;
#endif /* LWIP_UDP */
            }
            UNLOCK_TCPIP_CORE();

            pbuf_free(p);
        }
        else
        {
            err = ERR_MEM;
        }
    }
#else /* LWIP_TCPIP_CORE_LOCKING */
    /* initialize a buffer */
    buf.p = buf.ptr = NULL;
#if LWIP_CHECKSUM_ON_COPY
    buf.flags = 0;
#endif /* LWIP_CHECKSUM_ON_COPY */
    if (to)
    {
        inet_addr_to_ipaddr(&buf.addr, &to_in->sin_addr);
        remote_port           = ntohs(to_in->sin_port);
        netbuf_fromport(&buf) = remote_port;
    }
    else
    {
        remote_port           = 0;
        ip_addr_set_any(&buf.addr);
        netbuf_fromport(&buf) = 0;
    }

    LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_sendto(%d, data=%p, short_size=%"U16_F", flags=0x%x to=",
                                s, data, short_size, flags));
    ip_addr_debug_print(SOCKETS_DEBUG, &buf.addr);
    LWIP_DEBUGF(SOCKETS_DEBUG, (" port=%"U16_F"\n", remote_port));

    /* make the buffer point to the data that should be sent */
#if LWIP_NETIF_TX_SINGLE_PBUF
    /* Allocate a new netbuf and copy the data into it. */
    if (netbuf_alloc(&buf, short_size) == NULL)
    {
        err = ERR_MEM;
    }
    else
    {
#if LWIP_CHECKSUM_ON_COPY
        if (sock->conn->type != NETCONN_RAW)
        {
            u16_t chksum = LWIP_CHKSUM_COPY(buf.p->payload, data, short_size);
            netbuf_set_chksum(&buf, chksum);
            err = ERR_OK;
        }
        else
#endif /* LWIP_CHECKSUM_ON_COPY */
        {
            err = netbuf_take(&buf, data, short_size);
        }
    }
#else /* LWIP_NETIF_TX_SINGLE_PBUF */
    err = netbuf_ref(&buf, data, short_size);
#endif /* LWIP_NETIF_TX_SINGLE_PBUF */
    if (err == ERR_OK)
    {
        /* send the data */
        err = netconn_send(sock->conn, &buf);
    }

    /* deallocated the buffer */
    netbuf_free(&buf);
#endif /* LWIP_TCPIP_CORE_LOCKING */
    sock_set_errno(sock, err_to_errno(err));
    return (err == ERR_OK ? short_size : -1);
}

int
lwip_socket(int domain, int type, int protocol)
{
    struct netconn *conn;
    int i;

    LWIP_UNUSED_ARG(domain);

    /* create a netconn */
    switch (type)
    {
    case SOCK_RAW:
        conn = netconn_new_with_proto_and_callback(NETCONN_RAW, (u8_t)protocol, event_callback);
        LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_socket(%s, SOCK_RAW, %d) = ",
                                    domain == PF_INET ? "PF_INET" : "UNKNOWN", protocol));
        break;
    case SOCK_DGRAM:
        conn = netconn_new_with_callback( (protocol == IPPROTO_UDPLITE) ?
                                          NETCONN_UDPLITE : NETCONN_UDP, event_callback);
        LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_socket(%s, SOCK_DGRAM, %d) = ",
                                    domain == PF_INET ? "PF_INET" : "UNKNOWN", protocol));
        break;
    case SOCK_STREAM:
        conn = netconn_new_with_callback(NETCONN_TCP, event_callback);
        LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_socket(%s, SOCK_STREAM, %d) = ",
                                    domain == PF_INET ? "PF_INET" : "UNKNOWN", protocol));
        if (conn != NULL)
        {
            /* Prevent automatic window updates, we do this on our own! */
            netconn_set_noautorecved(conn, 1);
        }
        break;
    default:
        LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_socket(%d, %d/UNKNOWN, %d) = -1\n",
                                    domain, type, protocol));
        set_errno(EINVAL);
        return -1;
    }

    if (!conn)
    {
        LWIP_DEBUGF(SOCKETS_DEBUG, ("-1 / ENOBUFS (could not create netconn)\n"));
        set_errno(ENOBUFS);
        return -1;
    }

    i = alloc_socket(conn, 0);

    if (i == -1)
    {
        netconn_delete(conn);
        set_errno(ENFILE);
        return -1;
    }
    conn->socket = i;
    LWIP_DEBUGF(SOCKETS_DEBUG, ("%d\n", i));
    set_errno(0);
    return i;
}

int
lwip_write(int s, const void * data, size_t size)
{
    return lwip_send(s, data, size, 0);
}

/**
 * Go through the readset and writeset lists and see which socket of the sockets
 * set in the sets has events. On return, readset, writeset and exceptset have
 * the sockets enabled that had events.
 *
 * exceptset is not used for now!!!
 *
 * @param maxfdp1 the highest socket index in the sets
 * @param readset_in:    set of sockets to check for read events
 * @param writeset_in:   set of sockets to check for write events
 * @param exceptset_in:  set of sockets to check for error events
 * @param readset_out:   set of sockets that had read events
 * @param writeset_out:  set of sockets that had write events
 * @param exceptset_out: set os sockets that had error events
 * @return number of sockets that had events (read/write/exception) (>= 0)
 */
static int
lwip_selscan(int maxfdp1, fd_set * readset_in, fd_set * writeset_in, fd_set * exceptset_in,
             fd_set * readset_out, fd_set * writeset_out, fd_set * exceptset_out)
{
    int i, nready = 0;
    fd_set lreadset, lwriteset, lexceptset;
    struct lwip_sock *sock;
    SYS_ARCH_DECL_PROTECT(lev);

    FD_ZERO(&lreadset);
    FD_ZERO(&lwriteset);
    FD_ZERO(&lexceptset);

    /* Go through each socket in each list to count number of sockets which
       currently match */
    for(i = 0; i < maxfdp1; i++)
    {
        void *lastdata = NULL;
        s16_t rcvevent = 0;
        u16_t sendevent = 0;
        u16_t errevent = 0;
        /* First get the socket's status (protected)... */
        SYS_ARCH_PROTECT(lev);
        sock = tryget_socket(i);
        if (sock != NULL)
        {
            lastdata = sock->lastdata;
            rcvevent = sock->rcvevent;
            sendevent = sock->sendevent;
            errevent = sock->errevent;
        }
        SYS_ARCH_UNPROTECT(lev);
        /* ... then examine it: */
        /* See if netconn of this socket is ready for read */
        if (readset_in && FD_ISSET(i, readset_in) && ((lastdata != NULL) || (rcvevent > 0)))
        {
            FD_SET(i, &lreadset);
            LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_selscan: fd=%d ready for reading\n", i));
            nready++;
        }
        /* See if netconn of this socket is ready for write */
        if (writeset_in && FD_ISSET(i, writeset_in) && (sendevent != 0))
        {
            FD_SET(i, &lwriteset);
            LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_selscan: fd=%d ready for writing\n", i));
            nready++;
        }
        /* See if netconn of this socket had an error */
        if (exceptset_in && FD_ISSET(i, exceptset_in) && (errevent != 0))
        {
            FD_SET(i, &lexceptset);
            LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_selscan: fd=%d ready for exception\n", i));
            nready++;
        }
    }
    /* copy local sets to the ones provided as arguments */
    *readset_out = lreadset;
    *writeset_out = lwriteset;
    *exceptset_out = lexceptset;

    LWIP_ASSERT("nready >= 0", nready >= 0);
    return nready;
}

/**
 * Processing exceptset is not yet implemented.
 */
int
lwip_select(int maxfdp1, fd_set * readset, fd_set * writeset, fd_set * exceptset,
            struct timeval * timeout)
{
    u32_t waitres = 0;
    int nready;
    fd_set lreadset, lwriteset, lexceptset;
    u32_t msectimeout;
    struct lwip_select_cb select_cb;
    err_t err;
    int i;
    SYS_ARCH_DECL_PROTECT(lev);

    LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_select(%d, %p, %p, %p, tvsec=%"S32_F" tvusec=%"S32_F")\n",
                                maxfdp1, (void *)readset, (void *) writeset, (void *) exceptset,
                                timeout ? (s32_t)timeout->tv_sec : (s32_t) - 1,
                                timeout ? (s32_t)timeout->tv_usec : (s32_t) - 1));

    /* Go through each socket in each list to count number of sockets which
       currently match */
    nready = lwip_selscan(maxfdp1, readset, writeset, exceptset, &lreadset, &lwriteset, &lexceptset);

    /* If we don't have any current events, then suspend if we are supposed to */
    if (!nready)
    {
        if (timeout && timeout->tv_sec == 0 && timeout->tv_usec == 0)
        {
            LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_select: no timeout, returning 0\n"));
            /* This is OK as the local fdsets are empty and nready is zero,
               or we would have returned earlier. */
            goto return_copy_fdsets;
        }

        /* None ready: add our semaphore to list:
           We don't actually need any dynamic memory. Our entry on the
           list is only valid while we are in this function, so it's ok
           to use local variables. */

        select_cb.next = NULL;
        select_cb.prev = NULL;
        select_cb.readset = readset;
        select_cb.writeset = writeset;
        select_cb.exceptset = exceptset;
        select_cb.sem_signalled = 0;
        err = sys_sem_new(&select_cb.sem, 0);
        if (err != ERR_OK)
        {
            /* failed to create semaphore */
            set_errno(ENOMEM);
            return -1;
        }

        /* Protect the select_cb_list */
        SYS_ARCH_PROTECT(lev);

        /* Put this select_cb on top of list */
        select_cb.next = select_cb_list;
        if (select_cb_list != NULL)
        {
            select_cb_list->prev = &select_cb;
        }
        select_cb_list = &select_cb;
        /* Increasing this counter tells even_callback that the list has changed. */
        select_cb_ctr++;

        /* Now we can safely unprotect */
        SYS_ARCH_UNPROTECT(lev);

        /* Increase select_waiting for each socket we are interested in */
        for(i = 0; i < maxfdp1; i++)
        {
            if ((readset && FD_ISSET(i, readset)) ||
                    (writeset && FD_ISSET(i, writeset)) ||
                    (exceptset && FD_ISSET(i, exceptset)))
            {
                struct lwip_sock *sock = tryget_socket(i);
                LWIP_ASSERT("sock != NULL", sock != NULL);
                SYS_ARCH_PROTECT(lev);
                sock->select_waiting++;
                LWIP_ASSERT("sock->select_waiting > 0", sock->select_waiting > 0);
                SYS_ARCH_UNPROTECT(lev);
            }
        }

        /* Call lwip_selscan again: there could have been events between
           the last scan (whithout us on the list) and putting us on the list! */
        nready = lwip_selscan(maxfdp1, readset, writeset, exceptset, &lreadset, &lwriteset, &lexceptset);
        if (!nready)
        {
            /* Still none ready, just wait to be woken */
            if (timeout == 0)
            {
                /* Wait forever */
                msectimeout = 0;
            }
            else
            {
                msectimeout =  ((timeout->tv_sec * 1000) + ((timeout->tv_usec + 500) / 1000));
                if (msectimeout == 0)
                {
                    /* Wait 1ms at least (0 means wait forever) */
                    msectimeout = 1;
                }
            }

            waitres = sys_arch_sem_wait(&select_cb.sem, msectimeout);
        }
        /* Increase select_waiting for each socket we are interested in */
        for(i = 0; i < maxfdp1; i++)
        {
            if ((readset && FD_ISSET(i, readset)) ||
                    (writeset && FD_ISSET(i, writeset)) ||
                    (exceptset && FD_ISSET(i, exceptset)))
            {
                struct lwip_sock *sock = tryget_socket(i);
                LWIP_ASSERT("sock != NULL", sock != NULL);
                SYS_ARCH_PROTECT(lev);
                sock->select_waiting--;
                LWIP_ASSERT("sock->select_waiting >= 0", sock->select_waiting >= 0);
                SYS_ARCH_UNPROTECT(lev);
            }
        }
        /* Take us off the list */
        SYS_ARCH_PROTECT(lev);
        if (select_cb.next != NULL)
        {
            select_cb.next->prev = select_cb.prev;
        }
        if (select_cb_list == &select_cb)
        {
            LWIP_ASSERT("select_cb.prev == NULL", select_cb.prev == NULL);
            select_cb_list = select_cb.next;
        }
        else
        {
            LWIP_ASSERT("select_cb.prev != NULL", select_cb.prev != NULL);
            select_cb.prev->next = select_cb.next;
        }
        /* Increasing this counter tells even_callback that the list has changed. */
        select_cb_ctr++;
        SYS_ARCH_UNPROTECT(lev);

        sys_sem_free(&select_cb.sem);
        if (waitres == SYS_ARCH_TIMEOUT)
        {
            /* Timeout */
            LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_select: timeout expired\n"));
            /* This is OK as the local fdsets are empty and nready is zero,
               or we would have returned earlier. */
            goto return_copy_fdsets;
        }

        /* See what's set */
        nready = lwip_selscan(maxfdp1, readset, writeset, exceptset, &lreadset, &lwriteset, &lexceptset);
    }

    LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_select: nready=%d\n", nready));
return_copy_fdsets:
    set_errno(0);
    if (readset)
    {
        *readset = lreadset;
    }
    if (writeset)
    {
        *writeset = lwriteset;
    }
    if (exceptset)
    {
        *exceptset = lexceptset;
    }


    return nready;
}

/**
 * Callback registered in the netconn layer for each socket-netconn.
 * Processes recvevent (data available) and wakes up tasks waiting for select.
 */
static void
event_callback(struct netconn * conn, enum netconn_evt evt, u16_t len)
{
    int s;
    struct lwip_sock *sock;
    struct lwip_select_cb *scb;
    int last_select_cb_ctr;
    SYS_ARCH_DECL_PROTECT(lev);

    LWIP_UNUSED_ARG(len);

    /* Get socket */
    if (conn)
    {
        s = conn->socket;
        if (s < 0)
        {
            /* Data comes in right away after an accept, even though
             * the server task might not have created a new socket yet.
             * Just count down (or up) if that's the case and we
             * will use the data later. Note that only receive events
             * can happen before the new socket is set up. */
            SYS_ARCH_PROTECT(lev);
            if (conn->socket < 0)
            {
                if (evt == NETCONN_EVT_RCVPLUS)
                {
                    conn->socket--;
                }
                SYS_ARCH_UNPROTECT(lev);
                return;
            }
            s = conn->socket;
            SYS_ARCH_UNPROTECT(lev);
        }

        sock = get_socket(s);
        if (!sock)
        {
            return;
        }
    }
    else
    {
        return;
    }

    SYS_ARCH_PROTECT(lev);
    /* Set event as required */
    switch (evt)
    {
    case NETCONN_EVT_RCVPLUS:
        sock->rcvevent++;
        break;
    case NETCONN_EVT_RCVMINUS:
        sock->rcvevent--;
        break;
    case NETCONN_EVT_SENDPLUS:
        sock->sendevent = 1;
        break;
    case NETCONN_EVT_SENDMINUS:
        sock->sendevent = 0;
        break;
    case NETCONN_EVT_ERROR:
        sock->errevent = 1;
        break;
    default:
        LWIP_ASSERT("unknown event", 0);
        break;
    }

    if (sock->select_waiting == 0)
    {
        /* noone is waiting for this socket, no need to check select_cb_list */
        SYS_ARCH_UNPROTECT(lev);
        return;
    }

    /* Now decide if anyone is waiting for this socket */
    /* NOTE: This code goes through the select_cb_list list multiple times
       ONLY IF a select was actually waiting. We go through the list the number
       of waiting select calls + 1. This list is expected to be small. */

    /* At this point, SYS_ARCH is still protected! */
again:
    for (scb = select_cb_list; scb != NULL; scb = scb->next)
    {
        if (scb->sem_signalled == 0)
        {
            /* semaphore not signalled yet */
            int do_signal = 0;
            /* Test this select call for our socket */
            if (sock->rcvevent > 0)
            {
                if (scb->readset && FD_ISSET(s, scb->readset))
                {
                    do_signal = 1;
                }
            }
            if (sock->sendevent != 0)
            {
                if (!do_signal && scb->writeset && FD_ISSET(s, scb->writeset))
                {
                    do_signal = 1;
                }
            }
            if (sock->errevent != 0)
            {
                if (!do_signal && scb->exceptset && FD_ISSET(s, scb->exceptset))
                {
                    do_signal = 1;
                }
            }
            if (do_signal)
            {
                scb->sem_signalled = 1;
                /* Don't call SYS_ARCH_UNPROTECT() before signaling the semaphore, as this might
                   lead to the select thread taking itself off the list, invalidagin the semaphore. */
                sys_sem_signal(&scb->sem);
            }
        }
        /* unlock interrupts with each step */
        last_select_cb_ctr = select_cb_ctr;
        SYS_ARCH_UNPROTECT(lev);
        /* this makes sure interrupt protection time is short */
        SYS_ARCH_PROTECT(lev);
        if (last_select_cb_ctr != select_cb_ctr)
        {
            /* someone has changed select_cb_list, restart at the beginning */
            goto again;
        }
    }
    SYS_ARCH_UNPROTECT(lev);
}

/**
 * Unimplemented: Close one end of a full-duplex connection.
 * Currently, the full connection is closed.
 */
int
lwip_shutdown(int s, int how)
{
    struct lwip_sock *sock;
    err_t err;
    u8_t shut_rx = 0, shut_tx = 0;

    LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_shutdown(%d, how=%d)\n", s, how));

    sock = get_socket(s);
    if (!sock)
    {
        return -1;
    }

    if (sock->conn != NULL)
    {
        if (netconn_type(sock->conn) != NETCONN_TCP)
        {
            sock_set_errno(sock, EOPNOTSUPP);
            return EOPNOTSUPP;
        }
    }
    else
    {
        sock_set_errno(sock, ENOTCONN);
        return ENOTCONN;
    }

    if (how == SHUT_RD)
    {
        shut_rx = 1;
    }
    else if (how == SHUT_WR)
    {
        shut_tx = 1;
    }
    else if(how == SHUT_RDWR)
    {
        shut_rx = 1;
        shut_tx = 1;
    }
    else
    {
        sock_set_errno(sock, EINVAL);
        return EINVAL;
    }
    err = netconn_shutdown(sock->conn, shut_rx, shut_tx);

    sock_set_errno(sock, err_to_errno(err));
    return (err == ERR_OK ? 0 : -1);
}

static int
lwip_getaddrname(int s, struct sockaddr * name, socklen_t * namelen, u8_t local)
{
    struct lwip_sock *sock;
    struct sockaddr_in sin;
    ip_addr_t naddr;

    sock = get_socket(s);
    if (!sock)
    {
        return -1;
    }

    memset(&sin, 0, sizeof(sin));
    sin.sin_len = sizeof(sin);
    sin.sin_family = AF_INET;

    /* get the IP address and port */
    netconn_getaddr(sock->conn, &naddr, &sin.sin_port, local);

    LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_getaddrname(%d, addr=", s));
    ip_addr_debug_print(SOCKETS_DEBUG, &naddr);
    LWIP_DEBUGF(SOCKETS_DEBUG, (" port=%"U16_F")\n", sin.sin_port));

    sin.sin_port = htons(sin.sin_port);
    inet_addr_from_ipaddr(&sin.sin_addr, &naddr);

    if (*namelen > sizeof(sin))
    {
        *namelen = sizeof(sin);
    }

    MEMCPY(name, &sin, *namelen);
    sock_set_errno(sock, 0);
    return 0;
}

int
lwip_getpeername(int s, struct sockaddr * name, socklen_t * namelen)
{
    return lwip_getaddrname(s, name, namelen, 0);
}

int
lwip_getsockname(int s, struct sockaddr * name, socklen_t * namelen)
{
    return lwip_getaddrname(s, name, namelen, 1);
}

int
lwip_getsockopt(int s, int level, int optname, void * optval, socklen_t * optlen)
{
    err_t err = ERR_OK;
    struct lwip_sock *sock = get_socket(s);
    struct lwip_setgetsockopt_data data;

    if (!sock)
    {
        return -1;
    }

    if ((NULL == optval) || (NULL == optlen))
    {
        sock_set_errno(sock, EFAULT);
        return -1;
    }

    /* Do length and type checks for the various options first, to keep it readable. */
    switch (level)
    {

        /* Level: SOL_SOCKET */
    case SOL_SOCKET:
        switch (optname)
        {

        case SO_ACCEPTCONN:
        case SO_BROADCAST:
            /* UNIMPL case SO_DEBUG: */
            /* UNIMPL case SO_DONTROUTE: */
        case SO_ERROR:
        case SO_KEEPALIVE:
            /* UNIMPL case SO_CONTIMEO: */
#if LWIP_SO_SNDTIMEO
        case SO_SNDTIMEO:
#endif /* LWIP_SO_SNDTIMEO */
#if LWIP_SO_RCVTIMEO
        case SO_RCVTIMEO:
#endif /* LWIP_SO_RCVTIMEO */
#if LWIP_SO_RCVBUF
        case SO_RCVBUF:
#endif /* LWIP_SO_RCVBUF */
            /* UNIMPL case SO_OOBINLINE: */
            /* UNIMPL case SO_SNDBUF: */
            /* UNIMPL case SO_RCVLOWAT: */
            /* UNIMPL case SO_SNDLOWAT: */
#if SO_REUSE
        case SO_REUSEADDR:
        case SO_REUSEPORT:
#endif /* SO_REUSE */
        case SO_TYPE:
            /* UNIMPL case SO_USELOOPBACK: */
            if (*optlen < sizeof(int))
            {
                err = EINVAL;
            }
            break;

        case SO_NO_CHECK:
            if (*optlen < sizeof(int))
            {
                err = EINVAL;
            }
#if LWIP_UDP
            if ((sock->conn->type != NETCONN_UDP) ||
                    ((udp_flags(sock->conn->pcb.udp) & UDP_FLAGS_UDPLITE) != 0))
            {
                /* this flag is only available for UDP, not for UDP lite */
                err = EAFNOSUPPORT;
            }
#endif /* LWIP_UDP */
            break;

        default:
            LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_getsockopt(%d, SOL_SOCKET, UNIMPL: optname=0x%x, ..)\n",
                                        s, optname));
            err = ENOPROTOOPT;
        }  /* switch (optname) */
        break;

        /* Level: IPPROTO_IP */
    case IPPROTO_IP:
        switch (optname)
        {
            /* UNIMPL case IP_HDRINCL: */
            /* UNIMPL case IP_RCVDSTADDR: */
            /* UNIMPL case IP_RCVIF: */
        case IP_TTL:
        case IP_TOS:
            if (*optlen < sizeof(int))
            {
                err = EINVAL;
            }
            break;
#if LWIP_IGMP
        case IP_MULTICAST_TTL:
            if (*optlen < sizeof(u8_t))
            {
                err = EINVAL;
            }
            break;
        case IP_MULTICAST_IF:
            if (*optlen < sizeof(struct in_addr))
            {
                err = EINVAL;
            }
            break;
        case IP_MULTICAST_LOOP:
            if (*optlen < sizeof(u8_t))
            {
                err = EINVAL;
            }
            if (NETCONNTYPE_GROUP(sock->conn->type) != NETCONN_UDP)
            {
                err = EAFNOSUPPORT;
            }
            break;
#endif /* LWIP_IGMP */

        default:
            LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_getsockopt(%d, IPPROTO_IP, UNIMPL: optname=0x%x, ..)\n",
                                        s, optname));
            err = ENOPROTOOPT;
        }  /* switch (optname) */
        break;

#if LWIP_TCP
        /* Level: IPPROTO_TCP */
    case IPPROTO_TCP:
        if (*optlen < sizeof(int))
        {
            err = EINVAL;
            break;
        }

        /* If this is no TCP socket, ignore any options. */
        if (sock->conn->type != NETCONN_TCP)
            return 0;

        switch (optname)
        {
        case TCP_NODELAY:
        case TCP_KEEPALIVE:
#if LWIP_TCP_KEEPALIVE
        case TCP_KEEPIDLE:
        case TCP_KEEPINTVL:
        case TCP_KEEPCNT:
#endif /* LWIP_TCP_KEEPALIVE */
            break;

        default:
            LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_getsockopt(%d, IPPROTO_TCP, UNIMPL: optname=0x%x, ..)\n",
                                        s, optname));
            err = ENOPROTOOPT;
        }  /* switch (optname) */
        break;
#endif /* LWIP_TCP */
#if LWIP_UDP && LWIP_UDPLITE
        /* Level: IPPROTO_UDPLITE */
    case IPPROTO_UDPLITE:
        if (*optlen < sizeof(int))
        {
            err = EINVAL;
            break;
        }

        /* If this is no UDP lite socket, ignore any options. */
        if (sock->conn->type != NETCONN_UDPLITE)
        {
            return 0;
        }

        switch (optname)
        {
        case UDPLITE_SEND_CSCOV:
        case UDPLITE_RECV_CSCOV:
            break;

        default:
            LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_getsockopt(%d, IPPROTO_UDPLITE, UNIMPL: optname=0x%x, ..)\n",
                                        s, optname));
            err = ENOPROTOOPT;
        }  /* switch (optname) */
        break;
#endif /* LWIP_UDP && LWIP_UDPLITE*/
        /* UNDEFINED LEVEL */
    default:
        LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_getsockopt(%d, level=0x%x, UNIMPL: optname=0x%x, ..)\n",
                                    s, level, optname));
        err = ENOPROTOOPT;
    }  /* switch */


    if (err != ERR_OK)
    {
        sock_set_errno(sock, err);
        return -1;
    }

    /* Now do the actual option processing */
    data.sock = sock;
#ifdef LWIP_DEBUG
    data.s = s;
#endif /* LWIP_DEBUG */
    data.level = level;
    data.optname = optname;
    data.optval = optval;
    data.optlen = optlen;
    data.err = err;
    tcpip_callback(lwip_getsockopt_internal, &data);
    sys_arch_sem_wait(&sock->conn->op_completed, 0);
    /* maybe lwip_getsockopt_internal has changed err */
    err = data.err;

    sock_set_errno(sock, err);
    return err ? -1 : 0;
}

static void
lwip_getsockopt_internal(void * arg)
{
    struct lwip_sock *sock;
#ifdef LWIP_DEBUG
    int s;
#endif /* LWIP_DEBUG */
    int level, optname;
    void *optval;
    struct lwip_setgetsockopt_data *data;

    LWIP_ASSERT("arg != NULL", arg != NULL);

    data = (struct lwip_setgetsockopt_data *)arg;
    sock = data->sock;
#ifdef LWIP_DEBUG
    s = data->s;
#endif /* LWIP_DEBUG */
    level = data->level;
    optname = data->optname;
    optval = data->optval;

    switch (level)
    {

        /* Level: SOL_SOCKET */
    case SOL_SOCKET:
        switch (optname)
        {

            /* The option flags */
        case SO_ACCEPTCONN:
        case SO_BROADCAST:
            /* UNIMPL case SO_DEBUG: */
            /* UNIMPL case SO_DONTROUTE: */
        case SO_KEEPALIVE:
            /* UNIMPL case SO_OOBINCLUDE: */
#if SO_REUSE
        case SO_REUSEADDR:
        case SO_REUSEPORT:
#endif /* SO_REUSE */
            /*case SO_USELOOPBACK: UNIMPL */
            *(int *)optval = ip_get_option(sock->conn->pcb.ip, optname);
            LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_getsockopt(%d, SOL_SOCKET, optname=0x%x, ..) = %s\n",
                                        s, optname, (*(int *)optval ? "on" : "off")));
            break;

        case SO_TYPE:
            switch (NETCONNTYPE_GROUP(sock->conn->type))
            {
            case NETCONN_RAW:
                *(int *)optval = SOCK_RAW;
                break;
            case NETCONN_TCP:
                *(int *)optval = SOCK_STREAM;
                break;
            case NETCONN_UDP:
                *(int *)optval = SOCK_DGRAM;
                break;
            default: /* unrecognized socket type */
                *(int *)optval = sock->conn->type;
                LWIP_DEBUGF(SOCKETS_DEBUG,
                            ("lwip_getsockopt(%d, SOL_SOCKET, SO_TYPE): unrecognized socket type %d\n",
                             s, *(int *)optval));
            }  /* switch (sock->conn->type) */
            LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_getsockopt(%d, SOL_SOCKET, SO_TYPE) = %d\n",
                                        s, *(int *)optval));
            break;

        case SO_ERROR:
            /* only overwrite ERR_OK or tempoary errors */
            if ((sock->err == 0) || (sock->err == EINPROGRESS))
            {
                sock_set_errno(sock, err_to_errno(sock->conn->last_err));
            }
            *(int *)optval = sock->err;
            sock->err = 0;
            LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_getsockopt(%d, SOL_SOCKET, SO_ERROR) = %d\n",
                                        s, *(int *)optval));
            break;

#if LWIP_SO_SNDTIMEO
        case SO_SNDTIMEO:
            *(int *)optval = netconn_get_sendtimeout(sock->conn);
            break;
#endif /* LWIP_SO_SNDTIMEO */
#if LWIP_SO_RCVTIMEO
        case SO_RCVTIMEO:
            *(int *)optval = netconn_get_recvtimeout(sock->conn);
            break;
#endif /* LWIP_SO_RCVTIMEO */
#if LWIP_SO_RCVBUF
        case SO_RCVBUF:
            *(int *)optval = netconn_get_recvbufsize(sock->conn);
            break;
#endif /* LWIP_SO_RCVBUF */
#if LWIP_UDP
        case SO_NO_CHECK:
            *(int *)optval = (udp_flags(sock->conn->pcb.udp) & UDP_FLAGS_NOCHKSUM) ? 1 : 0;
            break;
#endif /* LWIP_UDP*/
        default:
            LWIP_ASSERT("unhandled optname", 0);
            break;
        }  /* switch (optname) */
        break;

        /* Level: IPPROTO_IP */
    case IPPROTO_IP:
        switch (optname)
        {
        case IP_TTL:
            *(int *)optval = sock->conn->pcb.ip->ttl;
            LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_getsockopt(%d, IPPROTO_IP, IP_TTL) = %d\n",
                                        s, *(int *)optval));
            break;
        case IP_TOS:
            *(int *)optval = sock->conn->pcb.ip->tos;
            LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_getsockopt(%d, IPPROTO_IP, IP_TOS) = %d\n",
                                        s, *(int *)optval));
            break;
#if LWIP_IGMP
        case IP_MULTICAST_TTL:
            *(u8_t *)optval = sock->conn->pcb.ip->ttl;
            LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_getsockopt(%d, IPPROTO_IP, IP_MULTICAST_TTL) = %d\n",
                                        s, *(int *)optval));
            break;
        case IP_MULTICAST_IF:
            inet_addr_from_ipaddr((struct in_addr *)optval, &sock->conn->pcb.udp->multicast_ip);
            LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_getsockopt(%d, IPPROTO_IP, IP_MULTICAST_IF) = 0x%"X32_F"\n",
                                        s, *(u32_t *)optval));
            break;
        case IP_MULTICAST_LOOP:
            if ((sock->conn->pcb.udp->flags & UDP_FLAGS_MULTICAST_LOOP) != 0)
            {
                *(u8_t *)optval = 1;
            }
            else
            {
                *(u8_t *)optval = 0;
            }
            LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_getsockopt(%d, IPPROTO_IP, IP_MULTICAST_LOOP) = %d\n",
                                        s, *(int *)optval));
            break;
#endif /* LWIP_IGMP */
        default:
            LWIP_ASSERT("unhandled optname", 0);
            break;
        }  /* switch (optname) */
        break;

#if LWIP_TCP
        /* Level: IPPROTO_TCP */
    case IPPROTO_TCP:
        switch (optname)
        {
        case TCP_NODELAY:
            *(int *)optval = tcp_nagle_disabled(sock->conn->pcb.tcp);
            LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_getsockopt(%d, IPPROTO_TCP, TCP_NODELAY) = %s\n",
                                        s, (*(int *)optval) ? "on" : "off") );
            break;
        case TCP_KEEPALIVE:
            *(int *)optval = (int)sock->conn->pcb.tcp->keep_idle;
            LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_getsockopt(%d, IPPROTO_IP, TCP_KEEPALIVE) = %d\n",
                                        s, *(int *)optval));
            break;

#if LWIP_TCP_KEEPALIVE
        case TCP_KEEPIDLE:
            *(int *)optval = (int)(sock->conn->pcb.tcp->keep_idle / 1000);
            LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_getsockopt(%d, IPPROTO_IP, TCP_KEEPIDLE) = %d\n",
                                        s, *(int *)optval));
            break;
        case TCP_KEEPINTVL:
            *(int *)optval = (int)(sock->conn->pcb.tcp->keep_intvl / 1000);
            LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_getsockopt(%d, IPPROTO_IP, TCP_KEEPINTVL) = %d\n",
                                        s, *(int *)optval));
            break;
        case TCP_KEEPCNT:
            *(int *)optval = (int)sock->conn->pcb.tcp->keep_cnt;
            LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_getsockopt(%d, IPPROTO_IP, TCP_KEEPCNT) = %d\n",
                                        s, *(int *)optval));
            break;
#endif /* LWIP_TCP_KEEPALIVE */
        default:
            LWIP_ASSERT("unhandled optname", 0);
            break;
        }  /* switch (optname) */
        break;
#endif /* LWIP_TCP */
#if LWIP_UDP && LWIP_UDPLITE
        /* Level: IPPROTO_UDPLITE */
    case IPPROTO_UDPLITE:
        switch (optname)
        {
        case UDPLITE_SEND_CSCOV:
            *(int *)optval = sock->conn->pcb.udp->chksum_len_tx;
            LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_getsockopt(%d, IPPROTO_UDPLITE, UDPLITE_SEND_CSCOV) = %d\n",
                                        s, (*(int *)optval)) );
            break;
        case UDPLITE_RECV_CSCOV:
            *(int *)optval = sock->conn->pcb.udp->chksum_len_rx;
            LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_getsockopt(%d, IPPROTO_UDPLITE, UDPLITE_RECV_CSCOV) = %d\n",
                                        s, (*(int *)optval)) );
            break;
        default:
            LWIP_ASSERT("unhandled optname", 0);
            break;
        }  /* switch (optname) */
        break;
#endif /* LWIP_UDP */
    default:
        LWIP_ASSERT("unhandled level", 0);
        break;
    } /* switch (level) */
    sys_sem_signal(&sock->conn->op_completed);
}

int
lwip_setsockopt(int s, int level, int optname, const void * optval, socklen_t optlen)
{
    struct lwip_sock *sock = get_socket(s);
    err_t err = ERR_OK;
    struct lwip_setgetsockopt_data data;

    if (!sock)
    {
        return -1;
    }

    if (NULL == optval)
    {
        sock_set_errno(sock, EFAULT);
        return -1;
    }

    /* Do length and type checks for the various options first, to keep it readable. */
    switch (level)
    {

        /* Level: SOL_SOCKET */
    case SOL_SOCKET:
        switch (optname)
        {

        case SO_BROADCAST:
            /* UNIMPL case SO_DEBUG: */
            /* UNIMPL case SO_DONTROUTE: */
        case SO_KEEPALIVE:
            /* UNIMPL case case SO_CONTIMEO: */
#if LWIP_SO_SNDTIMEO
        case SO_SNDTIMEO:
#endif /* LWIP_SO_SNDTIMEO */
#if LWIP_SO_RCVTIMEO
        case SO_RCVTIMEO:
#endif /* LWIP_SO_RCVTIMEO */
#if LWIP_SO_RCVBUF
        case SO_RCVBUF:
#endif /* LWIP_SO_RCVBUF */
            /* UNIMPL case SO_OOBINLINE: */
            /* UNIMPL case SO_SNDBUF: */
            /* UNIMPL case SO_RCVLOWAT: */
            /* UNIMPL case SO_SNDLOWAT: */
#if SO_REUSE
        case SO_REUSEADDR:
        case SO_REUSEPORT:
#endif /* SO_REUSE */
            /* UNIMPL case SO_USELOOPBACK: */
            if (optlen < sizeof(int))
            {
                err = EINVAL;
            }
            break;
        case SO_NO_CHECK:
            if (optlen < sizeof(int))
            {
                err = EINVAL;
            }
#if LWIP_UDP
            if ((sock->conn->type != NETCONN_UDP) ||
                    ((udp_flags(sock->conn->pcb.udp) & UDP_FLAGS_UDPLITE) != 0))
            {
                /* this flag is only available for UDP, not for UDP lite */
                err = EAFNOSUPPORT;
            }
#endif /* LWIP_UDP */
            break;
        default:
            LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_setsockopt(%d, SOL_SOCKET, UNIMPL: optname=0x%x, ..)\n",
                                        s, optname));
            err = ENOPROTOOPT;
        }  /* switch (optname) */
        break;

        /* Level: IPPROTO_IP */
    case IPPROTO_IP:
        switch (optname)
        {
            /* UNIMPL case IP_HDRINCL: */
            /* UNIMPL case IP_RCVDSTADDR: */
            /* UNIMPL case IP_RCVIF: */
        case IP_TTL:
        case IP_TOS:
            if (optlen < sizeof(int))
            {
                err = EINVAL;
            }
            break;
#if LWIP_IGMP
        case IP_MULTICAST_TTL:
            if (optlen < sizeof(u8_t))
            {
                err = EINVAL;
            }
            if (NETCONNTYPE_GROUP(sock->conn->type) != NETCONN_UDP)
            {
                err = EAFNOSUPPORT;
            }
            break;
        case IP_MULTICAST_IF:
            if (optlen < sizeof(struct in_addr))
            {
                err = EINVAL;
            }
            if (NETCONNTYPE_GROUP(sock->conn->type) != NETCONN_UDP)
            {
                err = EAFNOSUPPORT;
            }
            break;
        case IP_MULTICAST_LOOP:
            if (optlen < sizeof(u8_t))
            {
                err = EINVAL;
            }
            if (NETCONNTYPE_GROUP(sock->conn->type) != NETCONN_UDP)
            {
                err = EAFNOSUPPORT;
            }
            break;
        case IP_ADD_MEMBERSHIP:
        case IP_DROP_MEMBERSHIP:
            if (optlen < sizeof(struct ip_mreq))
            {
                err = EINVAL;
            }
            if (NETCONNTYPE_GROUP(sock->conn->type) != NETCONN_UDP)
            {
                err = EAFNOSUPPORT;
            }
            break;
#endif /* LWIP_IGMP */
        default:
            LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_setsockopt(%d, IPPROTO_IP, UNIMPL: optname=0x%x, ..)\n",
                                        s, optname));
            err = ENOPROTOOPT;
        }  /* switch (optname) */
        break;

#if LWIP_TCP
        /* Level: IPPROTO_TCP */
    case IPPROTO_TCP:
        if (optlen < sizeof(int))
        {
            err = EINVAL;
            break;
        }

        /* If this is no TCP socket, ignore any options. */
        if (sock->conn->type != NETCONN_TCP)
            return 0;

        switch (optname)
        {
        case TCP_NODELAY:
        case TCP_KEEPALIVE:
#if LWIP_TCP_KEEPALIVE
        case TCP_KEEPIDLE:
        case TCP_KEEPINTVL:
        case TCP_KEEPCNT:
#endif /* LWIP_TCP_KEEPALIVE */
            break;

        default:
            LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_setsockopt(%d, IPPROTO_TCP, UNIMPL: optname=0x%x, ..)\n",
                                        s, optname));
            err = ENOPROTOOPT;
        }  /* switch (optname) */
        break;
#endif /* LWIP_TCP */
#if LWIP_UDP && LWIP_UDPLITE
        /* Level: IPPROTO_UDPLITE */
    case IPPROTO_UDPLITE:
        if (optlen < sizeof(int))
        {
            err = EINVAL;
            break;
        }

        /* If this is no UDP lite socket, ignore any options. */
        if (sock->conn->type != NETCONN_UDPLITE)
            return 0;

        switch (optname)
        {
        case UDPLITE_SEND_CSCOV:
        case UDPLITE_RECV_CSCOV:
            break;

        default:
            LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_setsockopt(%d, IPPROTO_UDPLITE, UNIMPL: optname=0x%x, ..)\n",
                                        s, optname));
            err = ENOPROTOOPT;
        }  /* switch (optname) */
        break;
#endif /* LWIP_UDP && LWIP_UDPLITE */
        /* UNDEFINED LEVEL */
    default:
        LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_setsockopt(%d, level=0x%x, UNIMPL: optname=0x%x, ..)\n",
                                    s, level, optname));
        err = ENOPROTOOPT;
    }  /* switch (level) */


    if (err != ERR_OK)
    {
        sock_set_errno(sock, err);
        return -1;
    }


    /* Now do the actual option processing */
    data.sock = sock;
#ifdef LWIP_DEBUG
    data.s = s;
#endif /* LWIP_DEBUG */
    data.level = level;
    data.optname = optname;
    data.optval = (void *)optval;
    data.optlen = &optlen;
    data.err = err;
    tcpip_callback(lwip_setsockopt_internal, &data);
    sys_arch_sem_wait(&sock->conn->op_completed, 0);
    /* maybe lwip_setsockopt_internal has changed err */
    err = data.err;

    sock_set_errno(sock, err);
    return err ? -1 : 0;
}

static void
lwip_setsockopt_internal(void * arg)
{
    struct lwip_sock *sock;
#ifdef LWIP_DEBUG
    int s;
#endif /* LWIP_DEBUG */
    int level, optname;
    const void *optval;
    struct lwip_setgetsockopt_data *data;

    LWIP_ASSERT("arg != NULL", arg != NULL);

    data = (struct lwip_setgetsockopt_data *)arg;
    sock = data->sock;
#ifdef LWIP_DEBUG
    s = data->s;
#endif /* LWIP_DEBUG */
    level = data->level;
    optname = data->optname;
    optval = data->optval;

    switch (level)
    {

        /* Level: SOL_SOCKET */
    case SOL_SOCKET:
        switch (optname)
        {

            /* The option flags */
        case SO_BROADCAST:
            /* UNIMPL case SO_DEBUG: */
            /* UNIMPL case SO_DONTROUTE: */
        case SO_KEEPALIVE:
            /* UNIMPL case SO_OOBINCLUDE: */
#if SO_REUSE
        case SO_REUSEADDR:
        case SO_REUSEPORT:
#endif /* SO_REUSE */
            /* UNIMPL case SO_USELOOPBACK: */
            if (*(int *)optval)
            {
                ip_set_option(sock->conn->pcb.ip, optname);
            }
            else
            {
                ip_reset_option(sock->conn->pcb.ip, optname);
            }
            LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_setsockopt(%d, SOL_SOCKET, optname=0x%x, ..) -> %s\n",
                                        s, optname, (*(int *)optval ? "on" : "off")));
            break;
#if LWIP_SO_SNDTIMEO
        case SO_SNDTIMEO:
            netconn_set_sendtimeout(sock->conn, (s32_t) * (int *)optval);
            break;
#endif /* LWIP_SO_SNDTIMEO */
#if LWIP_SO_RCVTIMEO
        case SO_RCVTIMEO:
            netconn_set_recvtimeout(sock->conn, *(int *)optval);
            break;
#endif /* LWIP_SO_RCVTIMEO */
#if LWIP_SO_RCVBUF
        case SO_RCVBUF:
            netconn_set_recvbufsize(sock->conn, *(int *)optval);
            break;
#endif /* LWIP_SO_RCVBUF */
#if LWIP_UDP
        case SO_NO_CHECK:
            if (*(int *)optval)
            {
                udp_setflags(sock->conn->pcb.udp, udp_flags(sock->conn->pcb.udp) | UDP_FLAGS_NOCHKSUM);
            }
            else
            {
                udp_setflags(sock->conn->pcb.udp, udp_flags(sock->conn->pcb.udp) & ~UDP_FLAGS_NOCHKSUM);
            }
            break;
#endif /* LWIP_UDP */
        default:
            LWIP_ASSERT("unhandled optname", 0);
            break;
        }  /* switch (optname) */
        break;

        /* Level: IPPROTO_IP */
    case IPPROTO_IP:
        switch (optname)
        {
        case IP_TTL:
            sock->conn->pcb.ip->ttl = (u8_t)(*(int *)optval);
            LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_setsockopt(%d, IPPROTO_IP, IP_TTL, ..) -> %d\n",
                                        s, sock->conn->pcb.ip->ttl));
            break;
        case IP_TOS:
            sock->conn->pcb.ip->tos = (u8_t)(*(int *)optval);
            LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_setsockopt(%d, IPPROTO_IP, IP_TOS, ..)-> %d\n",
                                        s, sock->conn->pcb.ip->tos));
            break;
#if LWIP_IGMP
        case IP_MULTICAST_TTL:
            sock->conn->pcb.udp->ttl = (u8_t)(*(u8_t *)optval);
            break;
        case IP_MULTICAST_IF:
            inet_addr_to_ipaddr(&sock->conn->pcb.udp->multicast_ip, (struct in_addr *)optval);
            break;
        case IP_MULTICAST_LOOP:
            if (*(u8_t *)optval)
            {
                udp_setflags(sock->conn->pcb.udp, udp_flags(sock->conn->pcb.udp) | UDP_FLAGS_MULTICAST_LOOP);
            }
            else
            {
                udp_setflags(sock->conn->pcb.udp, udp_flags(sock->conn->pcb.udp) & ~UDP_FLAGS_MULTICAST_LOOP);
            }
            break;
        case IP_ADD_MEMBERSHIP:
        case IP_DROP_MEMBERSHIP:
        {
            /* If this is a TCP or a RAW socket, ignore these options. */
            struct ip_mreq *imr = (struct ip_mreq *)optval;
            ip_addr_t if_addr;
            ip_addr_t multi_addr;
            inet_addr_to_ipaddr(&if_addr, &imr->imr_interface);
            inet_addr_to_ipaddr(&multi_addr, &imr->imr_multiaddr);
            if(optname == IP_ADD_MEMBERSHIP)
            {
                data->err = igmp_joingroup(&if_addr, &multi_addr);
            }
            else
            {
                data->err = igmp_leavegroup(&if_addr, &multi_addr);
            }
            if(data->err != ERR_OK)
            {
                data->err = EADDRNOTAVAIL;
            }
        }
        break;
#endif /* LWIP_IGMP */
        default:
            LWIP_ASSERT("unhandled optname", 0);
            break;
        }  /* switch (optname) */
        break;

#if LWIP_TCP
        /* Level: IPPROTO_TCP */
    case IPPROTO_TCP:
        switch (optname)
        {
        case TCP_NODELAY:
            if (*(int *)optval)
            {
                tcp_nagle_disable(sock->conn->pcb.tcp);
            }
            else
            {
                tcp_nagle_enable(sock->conn->pcb.tcp);
            }
            LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_setsockopt(%d, IPPROTO_TCP, TCP_NODELAY) -> %s\n",
                                        s, (*(int *)optval) ? "on" : "off") );
            break;
        case TCP_KEEPALIVE:
            sock->conn->pcb.tcp->keep_idle = (u32_t)(*(int *)optval);
            LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_setsockopt(%d, IPPROTO_TCP, TCP_KEEPALIVE) -> %"U32_F"\n",
                                        s, sock->conn->pcb.tcp->keep_idle));
            break;

#if LWIP_TCP_KEEPALIVE
        case TCP_KEEPIDLE:
            sock->conn->pcb.tcp->keep_idle = 1000 * (u32_t)(*(int *)optval);
            LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_setsockopt(%d, IPPROTO_TCP, TCP_KEEPIDLE) -> %"U32_F"\n",
                                        s, sock->conn->pcb.tcp->keep_idle));
            break;
        case TCP_KEEPINTVL:
            sock->conn->pcb.tcp->keep_intvl = 1000 * (u32_t)(*(int *)optval);
            LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_setsockopt(%d, IPPROTO_TCP, TCP_KEEPINTVL) -> %"U32_F"\n",
                                        s, sock->conn->pcb.tcp->keep_intvl));
            break;
        case TCP_KEEPCNT:
            sock->conn->pcb.tcp->keep_cnt = (u32_t)(*(int *)optval);
            LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_setsockopt(%d, IPPROTO_TCP, TCP_KEEPCNT) -> %"U32_F"\n",
                                        s, sock->conn->pcb.tcp->keep_cnt));
            break;
#endif /* LWIP_TCP_KEEPALIVE */
        default:
            LWIP_ASSERT("unhandled optname", 0);
            break;
        }  /* switch (optname) */
        break;
#endif /* LWIP_TCP*/
#if LWIP_UDP && LWIP_UDPLITE
        /* Level: IPPROTO_UDPLITE */
    case IPPROTO_UDPLITE:
        switch (optname)
        {
        case UDPLITE_SEND_CSCOV:
            if ((*(int *)optval != 0) && ((*(int *)optval < 8) || (*(int *)optval > 0xffff)))
            {
                /* don't allow illegal values! */
                sock->conn->pcb.udp->chksum_len_tx = 8;
            }
            else
            {
                sock->conn->pcb.udp->chksum_len_tx = (u16_t) * (int *)optval;
            }
            LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_setsockopt(%d, IPPROTO_UDPLITE, UDPLITE_SEND_CSCOV) -> %d\n",
                                        s, (*(int *)optval)) );
            break;
        case UDPLITE_RECV_CSCOV:
            if ((*(int *)optval != 0) && ((*(int *)optval < 8) || (*(int *)optval > 0xffff)))
            {
                /* don't allow illegal values! */
                sock->conn->pcb.udp->chksum_len_rx = 8;
            }
            else
            {
                sock->conn->pcb.udp->chksum_len_rx = (u16_t) * (int *)optval;
            }
            LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_setsockopt(%d, IPPROTO_UDPLITE, UDPLITE_RECV_CSCOV) -> %d\n",
                                        s, (*(int *)optval)) );
            break;
        default:
            LWIP_ASSERT("unhandled optname", 0);
            break;
        }  /* switch (optname) */
        break;
#endif /* LWIP_UDP */
    default:
        LWIP_ASSERT("unhandled level", 0);
        break;
    }  /* switch (level) */
    sys_sem_signal(&sock->conn->op_completed);
}

int
lwip_ioctl(int s, long cmd, void * argp)
{
    struct lwip_sock *sock = get_socket(s);
    u8_t val;
#if LWIP_SO_RCVBUF
    u16_t buflen = 0;
    s16_t recv_avail;
#endif /* LWIP_SO_RCVBUF */

    if (!sock)
    {
        return -1;
    }

    switch (cmd)
    {
#if LWIP_SO_RCVBUF
    case FIONREAD:
        if (!argp)
        {
            sock_set_errno(sock, EINVAL);
            return -1;
        }

        SYS_ARCH_GET(sock->conn->recv_avail, recv_avail);
        if (recv_avail < 0)
        {
            recv_avail = 0;
        }
        *((u16_t *)argp) = (u16_t)recv_avail;

        /* Check if there is data left from the last recv operation. /maq 041215 */
        if (sock->lastdata)
        {
            struct pbuf *p = (struct pbuf *)sock->lastdata;
            if (netconn_type(sock->conn) != NETCONN_TCP)
            {
                p = ((struct netbuf *)p)->p;
            }
            buflen = p->tot_len;
            buflen -= sock->lastoffset;

            *((u16_t *)argp) += buflen;
        }

        LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_ioctl(%d, FIONREAD, %p) = %"U16_F"\n", s, argp, *((u16_t *)argp)));
        sock_set_errno(sock, 0);
        return 0;
#endif /* LWIP_SO_RCVBUF */

    case FIONBIO:
        val = 0;
        if (argp && *(u32_t *)argp)
        {
            val = 1;
        }
        netconn_set_nonblocking(sock->conn, val);
        LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_ioctl(%d, FIONBIO, %d)\n", s, val));
        sock_set_errno(sock, 0);
        return 0;

    default:
        LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_ioctl(%d, UNIMPL: 0x%lx, %p)\n", s, cmd, argp));
        sock_set_errno(sock, ENOSYS); /* not yet implemented */
        return -1;
    } /* switch (cmd) */
}

/** A minimal implementation of fcntl.
 * Currently only the commands F_GETFL and F_SETFL are implemented.
 * Only the flag O_NONBLOCK is implemented.
 */
int
lwip_fcntl(int s, int cmd, int val)
{
    struct lwip_sock *sock = get_socket(s);
    int ret = -1;

    if (!sock || !sock->conn)
    {
        return -1;
    }

    switch (cmd)
    {
    case F_GETFL:
        ret = netconn_is_nonblocking(sock->conn) ? O_NONBLOCK : 0;
        break;
    case F_SETFL:
        if ((val & ~O_NONBLOCK) == 0)
        {
            /* only O_NONBLOCK, all other bits are zero */
            netconn_set_nonblocking(sock->conn, val & O_NONBLOCK);
            ret = 0;
        }
        break;
    default:
        LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_fcntl(%d, UNIMPL: %d, %d)\n", s, cmd, val));
        break;
    }
    return ret;
}

#endif /* LWIP_SOCKET */
